Current research in postharvest biology of ornamentals and cut flowers Cai-Zhong Jiang USDA-ARSARS Michael Reid Department of Plant Sciences UC Davis Value of California s agriculture 2005 total $31.7 billion Fruits and nuts, $10.47 Vegetables & melons, $6.25 Livestock & poultry, $8.45 Greenhouse, Nursery & Floriculture, $3.44 Field crops, $3.09 Data from the California Department of Food and Agriculture. 1
Source and sales of cut flowers in the U.S. during the last three decades The postharvest problems Flowers are shipped long distances and stored for long times >25% product losses in marketing chain Flowers and potted plants don t last long enough International market, strong competition Lower consumer satisfaction. Customers don t return 2
Postharvest science Goal - reduce losses, increase quality, expand markets Understand factors involved in postharvest losses Develop better technologies to reduce losses _ Genetically- improved cultivars Factors affecting the postharvest life of ornamentals Temperature Disease Water supply Leaf yellowing and flower senescence Ethylene 3
Temperature - why is it important? Perishable products are alive Flowers have high respiration rates Vase life after transit and storage is directly correlated with the respiration rate at the storage temperature Improving the cold chain Transportation at low temperatures reduces respiration & improves the subsequent life of cut flowers 32 37 41 46 50 55 4
Temperature, respiration rate & vase life in stock flowers R e s p i r a t i o n ( m l C O 2 / k g h r ) 350 300 250 200 150 100 50 0 y = 0.0012x 4-0.0619x 3 + 1.2003x 2-3.6913x + 25.509 R 2 = 0.9974 0.0 5.0 10.0 15.0 20.0 25.0 30.0 Temperature (C) V a s e l i f e a f t e r s t o r a g e ( d a y s ) 9 8 7 6 5 4 3 2 1 y = -0.0299x + 7.1564 R 2 = 0.9426 0 0 50 100 150 200 250 Total CO2 respired during storage (x100) ml CO2/kg Effects of different shipping temperatures on potted Campanula plant quality 5
Effects of shipment temperature on flower senescence and bud abortion on potted Campanula plants 50.00 45.00 40.00 Number per inflorescence 35.00 30.00 25.00 20.00 15.00 10.00 5.00 Aborted buds 0.00 20 C Room 20 C 15C 10 C 5 C 0 C Fresh buds Wilted flowers Fresh flowers Advantages of decreased temperature in handling flowers 1. respiration 2. transpiration 3. ethylene production 4. ethylene susceptibility 5. disease growth (Botyrtis) 6. condensation 7. need for wet holding /packing 8. bending 9. flower development 10. color loss/yellowing 6
Cooling Forced air for cut flowers Potted plants could be vacuum cooled presently passive cooling if at all condensation! Works wonderfully 65 60 55 Room cooling 50 45 40 Downdraft cooling Cooler temperature 35 30 0 50 100 150 7
Vacuum cooling: a better approach to rapidly cool down potted plants The rapidity of vacuum cooling in less than 10 min vacuum Flower buds Soil & stems 8
Disease prevention Postharvest disease (primarily caused by gray mold (Botrytis cinerea) is a common cause of poor quality and shortened vase life Postharvest control strategies Disease life cycle The disease triangle Environment Pathogen Host 9
Environment Grey mold moisture watch for condensation (good temperature management) Spores accumulate on: Dead plant materials Cooler walls Time to infection (days) Genetic difference of disease resistance among rose genotypes 20 18 16 14 12 10 8 6 4 2 0 Bridal Akito 4372 3335 3419 4526 Vendela 4513 4040 4397 Blushing Akito Variety/code 4029 Dark Engagement 3358 3026 3378 4410 10
Commercial / Industry Sanitizers Plant Defense Compounds FDA GRAS/GRASE Designations Alternative uses for existing products Disease incidence (% of flowers infected) 100 No chlorine dioxide dip Plus chlorine dioxide dip 80 60 40 20 0 0 2 4 6 8 10 12 Time (days) Orlando rose flowers were dipped in 0 or 10 ppm Cl0 2? then shipped to Florida within 3 days. Vase life evaluation showed a significant reduction in Botrytis infection compared to non-dipped flowers. 11
Effective as a dip treatment 1-6% solution Phytotoxicity Using NaOCl to control Botrytis infection in cut rose 12
Effects of NaOCl treatment on Botrytis incidences during rose shipping Gold Strike Incidence (Akito) 100.0 100 Day 4 Day 4 Day 7 80.0 Day 7 80 60.0 60 40.0 40 20.0 20 0.0 No Dip H2O Dip Phyton 27 NaOCl 0 No Dip H2O Dip Phyton 27 NaOCl Tre atments Treatments Water supply Plants are mostly water (80-90%) Loss of water causes loss of quality wilting accelerated aging (ethylene production) 13
Water supply How do plants get water? Evaporation from leaves (transpiration) creates tension in the conducting system (xylem) Tension drags water from the soil or vase solution 14
Water supply Why do cut flowers wilt? Air embolism Bacterial contamination Why do potted plants wilt? Drought Waterlogging Air embolism blocks vessels 15
6/21/2010 Maintaining water supply Flowers recut under water use a preservative clean buckets Potted plants good medium water as needed allow to drain 16
An Alternative Postharvest Handling Strategy for Cut Flowers Dry Handling after Harvest 25 20 No hydration Plus Hydration 15 10 5 0 Black Magic Charlotte Freedom Osiana Vendela Application of ABA enhances display life of potted miniature rose plants 17
ABA treatments enhance display life of potted miniature rose plants Display life (days) 18 16 14 12 10 8 6 4 2 0 b a 0 10 20 50 a ABA concentration (ppm) a Application of ABA reduces Weight loss from potted miniature rose plants 100 90 0ppm 10ppm 20ppm 50ppm 80 Weight loss (% of day 0) 70 60 50 40 30 20 0 5 10 15 20 Time (days) 18
Leaf yellowing For many ornamentals, leaf yellowing during and after production is a serious quality issue Depending on the species, this problem can be overcome by application of the plant growth regulators, GA, BA, or a mixture of the two (recently registered as Fascination ) Thidiazuron (TDZ) Also known as Phenyl-N' N'-(1,2,3- thiadiazol-5-yl) urea. Has strong cytokinin activity. Used as a growth regulator in tissue culture Used as a cotton defoliant (Dropp) Is not metabolized, so remains active 19
Growth regulators delay leaf yellowing TDZ (thidiazuron), a non-metabolized cytokinin Effect of TDZ on leaf yellowing, flower opening and longevity in iris 0 µm TDZ 500 µm TDZ 0 µm TDZ 500 µm TDZ 20
Effects of TDZ on the leaves of Ornithogalum TDZ treatment after 30 days Control after 30 days Effects of TDZ on Cyclamen TDZ Control 21
Ethylene Some flowers and plants are very sensitive to ethylene (0.1 ppm) Ethylene is everywhere engines, ripening fruit, cigarette smoke Shouldn t be a problem STS, 1-MCP Techniques for inhibiting ethylene action Controlled atmospheres Low oxygen, high CO 2 inhibit production, action Chemicals-STS complex salt of silver nitrate, sodium thiosulfate used commercially with cut flowers, potted plants environmental issues - silver a heavy metal 22
STS MCP provides valuable protection for ornamentals 23
Avoiding ethylene effects: cultivar selection/engineering Choose insensitive cultivars Snapdragons, Carnations, Roses Modulate ethylene's role Anti-sense ACC synthase Etr mutants, anti-sense binding site Ethylene Biosynthesis 24
Example: Silencing a gene required for ethylene synthesis in petunias (ACC oxidase) TRV PhCHS/ACO TRV PhCHS/ACO TRV PhCHS Control Day 0 Day 3 Day 7 Ethylene biosynthesis and sensing/signaling 25
Overexpression of etr1-1 by inducible system extends flower longevity Overexpression of etr1-1 by inducible system extends flower longevity 26
Acknowledgments USDA BARD_Israel American Floral Endowment Joseph H. Hill Memorial Foundation Mellano & Company Kitayama Brothers Goldsmith Seeds Rosen Tantau 27